Band saws are customarily employed in industrial applications as tools for cutting metal. Such saws generally include a band saw head assembly having an endless saw band trained about a plurality of band wheels mounted for rotation on spaced parallel axes. One of the wheels about which the saw band is trained (the drive wheel) is power driven and drives the band by frictional engagement between the periphery of the wheel and one face of the band.
Power is transferred to the drive wheel through a gear assembly comprising an internal ring gear, i.e., one in which the teeth project inwardly from the inside periphery of the drive wheel, and a smaller pinion gear which is interconnected to a driving motor.
Band saws cut through metal at a very high rate of speed and thus generate metal chips as they cut through the metal workpiece. Although a number of cleaning systems are employed to remove these chips from the blade and band saw assembly, a quantity of metal chips eventually find their way into the gear assembly, despite all precautions. These chips, lodged between the gear teeth, accelerate the wear of the gear assembly with the result that the gears must be replaced relatively frequently.
In the conventional drive wheel assembly, the ring gear is integral with a unitary drive wheel. Thus, replacement of a worn ring gear can only be accomplished by replacing the entire drive wheel, large portions of which may be in satisfactory working condition. In view of the fact that such wheels are large, machine-formed balanced castings, replacement costs are substantial.